Juice from cane sugar has been conventionally clarified by the application of lime and heat followed by extended settling in large tanks. More recently, chemical polyacrylamides have been used to accelerate the coagulation and settling of these cane sugar juices, both in conventional large clarifying tanks and in smaller specially designed tanks to take advantage of the accelerated coagulation provided by polyacrylamide.
The nature of cane sugar juice is that the insoluble solids, which are precipitated by the conventional addition of lime and application of heat, are gummy and sticky. In addition, the natural variation in cane juice quality is such that the physical characteristics of the precipitate are variable. This variation makes it difficult to provide equipment, which will allow the clarification of cane sugar juice in the fastest manner when treated with polyacrylamide.
In normal processing, cane sugar juice is limed and heated with the pH of the juice increasing from a range of 5.0-6.5 to about 6.8-7.5. After liming, a dilute solution of polyacrylamide is then added to the juice to enhance coagulation. Various rapid clarifying apparatuses may be employed such as the "EIS Rapid Clarifier," U.S. Pat. No. 2,679,464; I.S.J. 1955, 57, 25 or the "SRI Clarifier," developed by the Sugar Research Institute of Australia.
Applicant's previously issued patent, U.S. Pat. No. 3,963,513, discloses a method and apparatus for increasing precipitate formation in cane sugar juice processing by treating downwardly flowing juice with milk of lime in a treating zone, and reducing the flow rate of the juice in a holding zone in a manner so as to avoid both the breakup of the particles and the settling out of those particles from the juice.